Automatic aggregation of inter-device ports/links in a virtual device

ABSTRACT

A virtual device includes multiple devices connected to operate as a single device. A first one of the devices is configured to determine that the first device connects to a second one of the devices via a first link; identify a second link; determine that the second link connects the first device to the second device; and automatically aggregate the first link and the second link to form a link aggregation with the second device based on determining that the first device connects to the second device via both the first and second links. The first device is further configured to transmit packets to the second device via the first and second links of the link aggregation.

BACKGROUND INFORMATION

A virtual device includes a collection of devices connected together tooperate as a single device. It is common to provide some redundancy inthe connections between the devices. Thus, if a particular link, betweentwo devices, goes down, then there exists another path via which the twodevices can communicate with each other.

SUMMARY

According to one implementation, a virtual device may include multipledevices connected to operate as a single device. A first one of thedevices may discover a second one of the devices, determine that thefirst device connects to the second device via multiple links, andautomatically aggregate the multiple links to form a link aggregationwith the second device based on determining that the first deviceconnects to the second device via the multiple links The first devicemay transmit traffic to the second device via each of the multiple linksof the link aggregation.

According to another implementation, a virtual system may includemultiple devices connected to operate as a single device. A first one ofthe devices (“first device”) may include means for determining that thefirst device is connected to a second one of the devices (“seconddevice”), means for determining that the first device connects to thesecond device via multiple links, means for automatically aggregatingthe links to form a link aggregation with the second device based ondetermining that the first device connects to the second device viamultiple links, and means for transmitting traffic to the second deviceover one or more of the links, of the link aggregation, using a loadbalancing technique.

According to a further implementation, a method may be performed by afirst device of a group of devices connected to operate as a singledevice. The method may include determining that the first deviceconnects to a second device, of the group of devices, via a first link;identifying a second link; determining that the second link connects thefirst device to the second device; automatically aggregating the firstlink and the second link to form a link aggregation with the seconddevice based on determining that the first device connects to the seconddevice via both the first and second links, and transmitting packets tothe second device via the first and second links of the linkaggregation, where one or more of the packets are transmitted via thefirst link and another one or more of the packets are transmitted viathe second link.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate one or more systems and/or methoddescribed herein and, together with the description, explain thesesystems and/or methods. In the drawings:

FIG. 1 is a diagram of a virtual device with redundant links betweendevices;

FIG. 2 is a diagram of an exemplary virtual device according to animplementation described herein;

FIG. 3A is a diagram illustrating a possible distributed deployment ofdevices, of a virtual device, within a building;

FIG. 3B is a diagram illustrating a possible distributed deployment ofdevices, of a virtual device, within a campus of buildings;

FIG. 4 is a diagram of exemplary components of a device of FIG. 2;

FIG. 5A is a diagram illustrating exemplary network ports of one or morenetwork interfaces of FIG. 4;

FIG. 5B is a diagram illustrating exemplary device ports of one or moredevice interfaces of FIG. 4;

FIG. 6 is a diagram illustrating exemplary functional components of thecontroller of FIG. 3;

FIG. 7 is a flowchart of an exemplary process for automaticallyaggregating ports of a virtual device;

FIG. 8 is a flowchart of an exemplary process for handling a statechange of a device link; and

FIG. 9 is a flowchart of an exemplary process for transmitting trafficwithin a virtual device.

DETAILED DESCRIPTION

The following detailed description refers to the accompanying drawings.The same reference numbers in different drawings may identify the sameor similar elements.

FIG. 1 is a diagram of a virtual device 100 with redundant links betweendevices. As shown in FIG. 1, virtual device 100 includes three devices110-1, 110-2, and 110-3 (collectively referred to as “devices 110,” andindividually as “device 110”) connected via an active link and a hotstandby link. For example, device 110-1 connects to device 110-2 via anactive link and a hot standby link and connects to device 110-3 via anactive link and a hot standby link; device 110-2 connects to device110-1 via an active link and a hot standby link and connects to device110-3 via an active link and a hot standby link; and device 110-3connects to device 110-1 via an active link and a hot standby link andconnects to device 110-2 via an active link and a hot standby link.

Device 110 may use the active link to transmit traffic to another device110. The hot standby link may be used in case of a failure on an activelink. When a failure occurs on an active link, a device 110 may causethe traffic, for the failed link, to be switched over to the hot standbylink. Some traffic loss occurs during the switch-over from the failedlink to the hot standby link. Also, bandwidth, on the links, is notfully utilized in that no traffic is transmitted on the hot standby linkunless a failure occurs on the active link.

According to an implementation described herein, a virtual device mayautomatically aggregate links between devices and transmit traffic overthe aggregated links. The term “traffic,” as used herein, may refer to asingle data packet and/or control packet, or a series of data packetsand/or control packets. The term “packet,” as used herein, is intendedto refer to any form or arrangement of information whether in packetform or in non-packet form.

FIG. 2 is a diagram of an exemplary virtual device 200 according to animplementation described herein. As shown in FIG. 2, virtual device 200may include a collection of devices 210-1, 210-2, and 210-3 (referred tocollectively as “devices 210,” and individually as “device 210”) thatoperate together as a single device. Device 210-1 may connect to device210-2 via a set of device links (shown as aggregated links), and mayconnect to device 210-3 via a set of device links (shown as aggregatedlinks). Device 210-2 may connect to device 210-1 via a set of devicelinks (shown as aggregated links), and may connect to device 210-3 via aset of device links (shown as aggregated links). Device 210-3 mayconnect to device 210-1 via a set of device links (shown as aggregatedlinks), and may connect to device 210-2 via a set of device links (shownas aggregated links).

While FIG. 2 shows a particular quantity of devices 210, the particularquantity of devices 210 is purely for illustration purposes. Inpractice, there may be fewer or additional devices 210 forming virtualdevice 200. Also, while FIG. 2 shows a particular topology of devices210, the particular topology is purely for illustration purposes. Inpractice, the topology of devices 210, of virtual device 200, maydiffer. For example, there may be fewer or additional device linksconnecting any two devices 210. Further, the quantity of device linksconnecting one set of devices 210 may differ from the quantity of devicelinks connecting another set of devices 210. Also, a particular device210 may connect, via one or more device links, to one other device 210,or two or more other devices 210 in another implementation.

Device 210 may include a network device, such as a routing device, aswitching device, a firewall device, a server device, or the like, or anon-network device, such as a computing device. While devices 210 can beimplemented as different types of devices, in the following paragraphs,devices 210 will be described in terms of a network device.

As shown in FIG. 2, each device 210 may include a number of ports, suchas one or more network ports (NW P) and/or one or more device ports (DEVP). A network port may include a port that connects to a link, such as anetwork link, that connects to a device external to virtual device 200.A device port may include a port that connects to a link, such as adevice link, that connects one device 210 to another device 210 withinvirtual device 200.

Devices 210, of virtual device 200, may be physically located on one ormore racks in one or more buildings. Devices 210 may be physicallylocated next to each other or separated by distances of up to 100 km ormore (e.g., between 50 to 100 km). FIG. 3A is a diagram illustrating apossible distributed deployment of devices 210, of virtual device 200,within a building. For example, as shown in FIG. 3A, devices 210-1,210-2, and 210-3 may be located on different floors of the building, andconnected to form virtual device 200. FIG. 3B is a diagram illustratinga possible distributed deployment of devices 210, of a virtual device200, within a campus of buildings. For example, as shown in FIG. 3B,devices 210-1, 210-2, and 210-3 may be located in different buildings,and connected to form virtual device 200.

FIG. 4 is a diagram of exemplary components of a device 210. As shown inFIG. 4, device 210 may include network interfaces 410-1, . . . , 410-N(collectively referred to as “network interfaces 410,” and individuallyas “network interface 410”) (where N>1), device interfaces 420-1, . . ., 420-M (collectively referred to as “device interfaces 420,” andindividually as “device interface 420”) (where M>1), switch fabric 430,and controller 440. In another implementation, device 210 may includefewer, additional, different, or differently arranged components thanthose illustrated in FIG. 4. Also, a function described as beingperformed by one of the components may be alternatively performed byanother one of the components.

Network interface 410 may include a component to receive, transmit,and/or process traffic on a network link. For example, network interface410 may include an Ethernet interface, an optical carrier (OC)interface, an asynchronous transfer mode (ATM) interface, or anothertype of interface. Network interface 410 may manage a set of one or moreinput ports via which packets can be received, a set of one or moreoutput ports via which packets can be transmitted, and/or a set of oneor more input/output ports via which packets can be received andtransmitted. In one implementation, a network interface 410 may functionas an input interface that receives packets on the network link andprocesses the packets. In another implementation, a network interface410 may function as an output interface that processes packets andtransmits the packets on the network link. In yet anotherimplementation, a network interface 410 may function as both an inputinterface and an output interface.

FIG. 5A is a diagram illustrating exemplary network ports 510 of one ormore network interfaces 410. Network ports 510 may be visible on theexterior structure of device 210. Network ports 510, illustrated in FIG.5A, may be associated with one or more network interfaces 410. A networkport 510 may be capable of transmitting packets for long distances(e.g., up to 100 km or more). In one implementation, a network port 510may be converted to a port for a device interface 420. This may bebeneficial to provide additional bandwidth for inter-device 210communications, and/or to facilitate the connection of devices 210 atlong distances.

Returning to FIG. 4, device interface 420 may include a component toreceive, transmit, and/or process traffic on a device link (i.e., a linkconnecting two devices 210). For example, device interface 410 mayinclude an Ethernet interface, an OC interface, or another type ofinterface. Device interface 420 may manage a set of one or more inputports via which packets can be received, a set of one or more outputports via which packets can be transmitted, and/or a set of one or moreinput/output ports via which packets can be received and transmitted. Inone implementation, device interface 420 may function as an inputinterface that receives packets on a device link and processes thepackets. In another implementation, device interface 420 may function asan output interface that processes packets and transmits the packets ona device link. In yet another implementation, device interface 420 mayfunction as both an input interface and an output interface.

FIG. 5B is a diagram illustrating exemplary ports 520 of one or moredevice interfaces 420. Device ports 520 may be visible on the exteriorstructure of device 210. Device ports 520, illustrated in FIG. 5B, maybe associated with one or more device interfaces 420.

Returning to FIG. 4, switch fabric 430 may include one or more switchingplanes to facilitate communication among interfaces 410/420 and/orcontroller 440. In one implementation, each of the switching planes mayinclude a single or multi-stage switch of crossbar elements. In anotherimplementation, each of the switching planes may include some other formof switching elements. Switch fabric 430 may also, or alternatively,include processors, memories, and/or paths that permit communicationamong controller 440 and interfaces 410/420.

Controller 440 may include one or more processors, microprocessors,application specific integrated circuits (ASICs), field programming gatearrays (FPGAs), and/or processing logic that may be optimized fornetworking and/or communications. Controller 440 may also include astatic memory (e.g. a read only memory (ROM)), a dynamic memory (e.g. arandom access memory (RAM)), onboard cache, and/or flash memory forstoring data and/or machine-readable instructions. Controller 440 maycommunicate with other devices 210, of virtual device 200, to exchangeinformation regarding the topology of virtual device 200 and/or tomonitor the state of the device links. In one implementation, controller440 may create a routing table based on the topology of virtual device200, create a forwarding table based on the routing table, and makingforwarding decisions based on the forwarding table.

As described below, controller 440 may automatically determine whendevice 210 (of which controller 440 is a component) connects to anotherdevice via more than one device link. In this case, controller 440 mayaggregate traffic on the device links, thereby making efficient use ofthe bandwidth that exists between two devices 210 of virtual device 200.

FIG. 6 is a diagram illustrating exemplary functional components ofcontroller 440. As shown in FIG. 6, controller 440 may include virtualdevice daemon 610, a routing table 620, a forwarding table 630, and aconnection table 640. In another implementation, controller 440 mayinclude fewer, additional, or different functional components than areshown in FIG. 6. Furthermore, a function described as being performed byone of the functional components may be alternatively performed byanother functional component.

Virtual device daemon 610 may discover neighboring devices 210, mayidentify adjacencies, may aggregate device links, and/or may monitor thestate (e.g., link up or down state) of the device links For example,virtual device daemon 610 may send hello packets on the device links todiscover neighboring devices 210. Virtual device daemon 610 may thenperform a handshaking operation with a neighboring device 210. Virtualdevice daemon 610 may identify adjacencies by identifying which deviceport 520 connects to which neighboring device 210. Based on theadjacencies, virtual device daemon 610 may identify device links thatcan be aggregated. For example, if virtual device daemon 610 determinesthat device 210 (with which virtual device daemon 610 is associated)connects to a particular device 210 via device port 1 and device port 3,virtual device daemon 610 may determine that device ports 1 and 3 can beaggregated, thereby aggregating the device links connected to deviceports 1 and 3.

Virtual device daemon 610 may generate and/or update routing table 620based on the topology of virtual device 200. For example, virtual devicedaemon 610 may obtain information, regarding the topology of virtualdevice 200, from other devices 210 in virtual device 200. Virtual devicedaemon 610 may also obtain information, from devices 210, regarding thenetwork links and/or device links to which devices 210 connect. Virtualdevice daemon 610 may store at least some of this information in routingtable 620. Virtual device daemon 610 may use routing table 620 toidentify, for example, an egress device 210 to which a received packetis to be sent before the packet exits virtual device 200.

Virtual device daemon 610 may generate forwarding table 630 based onrouting table 620. For example, virtual device daemon 610 may identify aparticular (next hop) device 210 to which to send a packet that isintended for an egress device 210. Virtual device daemon 610 mayperiodically perform a shortest path calculation (i.e., identify a pathto use to reach a particular egress device 210) and store the result ofthe calculation in forwarding table 630. A technique for performing ashortest path calculation includes, among others, the Dijkstra algorithmor the Bellman-Ford algorithm. The shortest path calculation may takeinto account, not only the number of hops to reach a particular egressdevice 210, but also the cost of taking each of these hops. The cost oftraversing a device link may be a function of the bandwidth available onthat device link. In the case of a link aggregation, the cost may be afunction of the combined bandwidth of the aggregated device links.

In one implementation, virtual device daemon 610 may perform a newshortest path calculation each time that the topology of virtual device200 changes (e.g., when a device link comes up or goes down, when a newdevice 210 is added, etc.). In another implementation, virtual devicedaemon 610 may perform a shortest path calculation at another time thatmay be independent of the changing of the topology of virtual device200. In one implementation, forwarding table 630 may store informationthat identifies a particular (next hop) device 210 for a particularegress device 210.

Virtual device daemon 610 may generate and/or update connection table640 based on the identified adjacencies and determined device linkaggregations. For example, virtual device daemon 610 may determine thattwo device links can be aggregated and may store information regardingthe device link aggregation in connection table 640.

Connection table 640 may include a device identifier (ID) field 642, atrunk ID field 644, and one or more port ID fields 646. In anotherimplementation, connection table 640 may contain fewer, additional, ordifferent fields than are shown in FIG. 6.

Device ID field 642 may store information identifying a neighboringdevice 210, such as a numerical identifier, an address, or some otherinformation that uniquely identifies a device 210 in virtual device 200.Trunk ID field 644 may store information (e.g., a trunk identifier)identifying a particular adjacency with neighboring device 210identified in device ID field 642. In the case of a link aggregation(i.e., two or more device links) that exists with neighboring device 210identified in device ID field 642, the trunk identifier may representthe combination of two or more device ports 520 associated with the linkaggregation. In the case of no link aggregation that exists withneighboring device 210, the trunk identifier may represent the singledevice port 520 associated with the device link connecting toneighboring device 210. Port ID field 646 may store information thatuniquely identifies a device port 520 to which neighboring device 210,identified in device ID field 642, connects via a device link. When alink aggregation exists with neighboring device 210, then one or moreother port ID fields 646 may store information that uniquely identifiesother device ports 520 to which neighboring device 210, identified indevice ID field 642, connects via a device link.

Virtual device daemon 610 may program one or more components of device210 with the information in connection table 630 so that these one ormore components may utilize the bandwidth of the link aggregation bytransmitting packets (e.g., control and/or data packets) over all of thedevice links of the link aggregation.

FIG. 7 is a flowchart of an exemplary process 700 for automaticallyaggregating ports of a virtual device. Process 700 may be performed by adevice 210 in virtual device 200. In one implementation, process 700 maybe performed separately by each device 210 in virtual device 200. Forthe description to follow, process 700 will be described as beingperformed by a particular device 210 of virtual device 200.

Process 700 may include discovering neighboring devices 210 (block 710).For example, virtual device daemon 610, of the particular device 210,may be notified, by another component of the particular device 210, ofan active device link (i.e., a device link that is in the up state). Inother words, when a device interface 320 determines that an activedevice link is connected to one of its device ports 520, deviceinterface 320 may notify virtual device daemon 610. Virtual devicedaemon 610 may transmit hello packets on all active device links. Aneighboring device 210, that receives a hello packet, may respond to thehello packet with a reply (e.g., an acknowledgement).

In response to a reply from a neighboring device 210, virtual devicedaemon 610 may perform a three-way handshake with a virtual devicedaemon 610 of the neighboring device 210 (hereinafter “neighboringvirtual device daemon 610”). For example, virtual device daemon 610 maysend a packet to neighboring virtual device daemon 610 indicating thatthe particular device 210 has seen the neighboring device 210 for thefirst time. The neighboring virtual device daemon 610 may respond bysending a packet, back to virtual device daemon 610, indicating that theneighboring device 210 has also seen the particular device 210. Virtualdevice daemon 610 may send another packet to neighboring virtual devicedaemon 610 confirming that the particular device 210 has seen theneighboring device 210 and that the neighboring device 210 has seen theparticular device 210, thereby completing the three-way handshake.

Adjacencies may be identified (block 720). For example, virtual devicedaemon 610 may identify, for each of the neighboring devices 210 thatvirtual device daemon 610 has discovered, a device port 520 via whichthe particular device 210 connects to the neighboring device 210 via adevice link. As a result of identifying the adjacencies, virtual devicedaemon 610 may know which neighboring devices 210 that the particulardevice 210 connects to and via which device ports 520.

Device ports 520, associated with a same neighboring device 210, may beaggregated (block 730). For example, virtual device daemon 610 mayidentify a neighboring device 210 to which the particular device 210connects via multiple device ports 520. In this case, virtual devicedaemon 610 may aggregate the multiple device ports 520, therebyaggregating the bandwidth available on the device links connected tothese multiple device ports 520.

Connection table 640 may be updated (block 740). For example, virtualdevice daemon 610 may create, or update, an entry in connection table640 to reflect the link aggregation of the multiple device ports 520.For aggregated device ports 520, virtual device daemon 610 may assign atrunk identifier to the link aggregation. Virtual device daemon 610 maystore information identifying the neighboring node 210 in device IDfield 642, the trunk identifier in trunk ID field 644, and informationidentifying the multiple device ports 520 in port ID fields 646.

Virtual device daemon 610 may create, or update, an entry in connectiontable 640 for each device port 520 via which the particular device 210connects to a neighboring device 210, regardless of whether that deviceport 520 has been aggregated. For a non-aggregated device port 520,virtual device daemon 610 may assign a trunk identifier to thenon-aggregated device port 520. Virtual device daemon 610 may storeinformation identifying the neighboring node 210 in device ID field 642,the trunk identifier in trunk ID field 644, and information identifyingthe non-aggregated device port 520 in port ID field 646.

One or more device components may be programmed to distribute trafficbased on connection table 640 (block 750). For example, virtual devicedaemon 610 may program one or more hardware components, of theparticular device 210, to distribute traffic based on the information inconnection table 640. For a link aggregation, the one or more hardwarecomponents may distribute traffic, on the device links, using a loadbalancing technique or some other technique that may attempt to fullyutilize the bandwidth on the device links.

FIG. 8 is a flowchart of an exemplary process 800 for handling a statechange of a device link. Process 800 may be performed by a device 210 invirtual device 200. In one implementation, process 800 may be performedseparately by each device 210 in virtual device 200. For the descriptionto follow, process 800 will be described as being performed by aparticular device 210 of virtual device 200.

Process 800 may include periodically sending ping messages on the devicelinks (block 810). For example, virtual device daemon 610 mayperiodically (e.g., at some designated frequency) transmit ping messages(e.g., hello and/or keep alive packets) on all of the device links towhich its device ports 520 connect. The purpose of the ping messages isto monitor the state of the device links. Device links can be generallyin one of two states: a link up state or a link down state. The link upstate may reflect that the device link is operable and the components,on a neighboring device 210 connected to that device link, are operableand capable of communicating on the device link. The link down state mayreflect that either the device link has failed (i.e., the device link isinoperable) or that the components, on a neighboring device 210connected to that device link, have failed (i.e., the device link isoperable, but a soft failure or a component failure has occurred atneighboring device 210). Thus, the ping messages can detect these softfailures or component failures that do not actually cause the devicelink to become inoperable.

The state of the device links may be determined (block 820), and achange in the state of the device links may be identified (block 830).For example, virtual device daemon 610 may determine whether responseswere received on the device links in response to the ping messages. Inone implementation, virtual device daemon 610 may identify that a devicelink is in the down state when a single response has not been receivedon that device link. In another implementation, virtual device daemon610 may identify that a device link is in the down state when noresponse has been received on that device link for a particular numberof ping messages transmitted on that device link. For example, virtualdevice daemon 610 may determine that a device link is in the down statewhen no response has been received for three consecutive ping messages.

When there is a change in the link state of a device link, virtualdevice daemon 610 may update forwarding table 630 (block 840). Forexample, virtual device daemon 610 may perform a new shortest pathcalculation based on the change in the link state. When a device link,of a link aggregation, changes to the down state, then virtual devicedaemon 610 may change the cost of transmitting traffic over theremaining device link(s) as a function of the bandwidth of the remainingdevice link(s). When a device link changes to the up state (e.g., when adevice link that was previously in the down state changes to the upstate or when a new device link is added), virtual device daemon 610 maychange the cost of transmitting traffic over the device link as afunction of the bandwidth of the device link. If the device link forms alink aggregation with one or more other device links, then virtualdevice daemon 610 may change the cost of transmitting over the linkaggregation as a function of the bandwidth of the link aggregation.Virtual device daemon 610 may perform a new shortest path calculationbased on the changed cost. Virtual device daemon 610 may updateforwarding table 630, if necessary, based on the new calculations.

When there is a change in the link state of a device link, virtualdevice daemon 610 may also update connection table 640 (block 850). Inone implementation, virtual device daemon 610 may update its adjacenciesby, for example, identifying a new adjacency, removing apreviously-identified adjacency, or changing an existing adjacency. As aresult of updating the adjacencies, virtual device daemon 610 may knowwhich neighboring devices 210 that the particular device 210 connects toand via which device ports 520.

Virtual device daemon 610 may identify a neighboring device 210 to whichthe particular device 210 connects via multiple device ports 520, aneighboring device 210 to which the particular device 210 connects via asingle device port 520, and/or a neighboring device 210 to which theparticular device 210 no longer connects, For a neighboring device 210to which the particular device 210 connects via multiple device ports520, virtual device daemon 610 may aggregate the multiple device ports520, thereby aggregating the bandwidth available on the device linksconnected to these multiple device ports 520.

Virtual device daemon 610 may update connection table 640 based on theupdating of the adjacencies. For example, virtual device daemon 610 maycreate, update, or remove an entry in connection table 640 to reflectthe updated adjacencies. For a new link aggregation, virtual devicedaemon 610 may assign a trunk identifier to the link aggregation. In oneimplementation, virtual device daemon 610 may create a new entry inconnection table 640 for the link aggregation and remove an existingentry relating to a device port 520 of the new aggregation. In anotherimplementation, virtual device daemon 610 may update the existing entry,in connection table 640, to reflect the new link aggregation. In eitherevent, the entry, in connection table 640, may store informationidentifying the neighboring node 210 in device ID field 642, the trunkidentifier in trunk ID field 644, and information identifying themultiple device ports 520 in port ID fields 646.

For a change to an existing link aggregation, virtual device daemon 610may update the entry, in connection table 640, corresponding to the linkaggregation. For example, virtual device daemon 610 may deleteinformation regarding one or more device ports 520 that is/are no longerpart of the link aggregation. This may result in one or more deviceports 520 continuing to connect to neighboring device 210 associatedwith the entry in connection table 640. For an adjacency that no longerexists, virtual device daemon 610 may remove an entry from connectiontable 640.

One or more device components may be programmed to distribute trafficbased on connection table 640 (block 860). For example, virtual devicedaemon 610 may program one or more hardware components, of theparticular device 210, to distribute traffic based on the information inconnection table 640. In the case of a link aggregation, the one or morehardware components may distribute traffic, on the device links of thelink aggregation, using a load balancing technique or some othertechnique that may attempt to fully utilize the bandwidth on the devicelinks In the case of no link aggregation, then the one or more hardwarecomponents may transmit traffic over the device link connected to theneighboring device 210. As a result, practically no traffic is lost dueto a change in the device link state.

FIG. 9 is a flowchart of an exemplary process for transmitting a packetwithin virtual device 200. Process 900 may be performed by a device 210in virtual device 200. In one implementation, process 900 may beperformed separately by each device 210 in virtual device 200. For thedescription to follow, process 900 will be described as being performedby a particular device 210 of virtual device 200.

Process 900 may include receiving traffic (block 910). For example,assume that the particular device 210 receives traffic (e.g., a datapacket or a control packet) on a network link via a network port 510 ofa network interface 310. The traffic may include certain information,such as information identifying the destination of the traffic (e.g., anaddress of the destination of the traffic).

An egress device 210, within virtual device 200, for the traffic may beidentified (block 920). For example, the particular device 210 mayperform a lookup operation in routing table 620 to determine, based onthe destination of the traffic, the identity of an egress device 210 viawhich the traffic is to be transmitted for the traffic to reach thedestination. In one implementation, the particular device 210 may usethe information regarding the destination of the traffic to identify adevice 210 (i.e., the egress device 210), within virtual device 200,that has the network port 510 via which the traffic is to betransmitted.

The next hop device 210, to which to forward the traffic, may beidentified (block 930). For example, the particular device 210 mayperform a lookup operation in forwarding table 630 to determine, basedon the identity of egress device 210, the identity of a next hop device210 via which the traffic is to be transmitted for the traffic to reachegress device 210 based on its shortest path calculation. In oneimplementation, the particular device 210 may use the informationregarding the egress device 210 to identify a device 210 (i.e., the nexthop device 210), within virtual device 200, to which the traffic is tobe transmitted.

A device trunk, via which to transmit the traffic, may be identified(block 940). For example, the particular device 210 may determine, basedon information from connection table 630 and based on the identity ofnext hop device 210, the identity of a device trunk via which thetraffic is to be transmitted for the traffic to reach next hop device210. As described above, a device trunk may correspond to a singledevice port 520 or an aggregation of multiple device ports 520.

The traffic may be forwarded to the next hop device 210 via one or moredevice ports 520 associated with the device trunk (block 950). Forexample, as described above, in a situation where the device trunkcorresponds to a device link aggregation, one or more hardwarecomponents of the particular device 210 may be programmed to use a loadbalancing technique, or the like, to distribute the traffic over themultiple device ports 520 associated with the device link aggregation.In a situation where the device trunk corresponds to a single devicelink, one or more hardware components of the particular device 210, maybe programmed to transmit data via the device port 530 associated withthe single device link. A device interface 320, responsible for theidentified device port(s) 520, may receive the traffic and output thetraffic on the device link(s) connected to the identified device port(s)520.

If the next hop device 210 is the egress device, the egress device 210may process the traffic and transmit the traffic on a network link,where the traffic exits virtual device 200. If the next hop device 210is not the egress device, the next hop device 210 may process thetraffic in a manner similar to that described above and forward thetraffic to another next hop device 210 or the egress device 210.Eventually, when the traffic reaches the egress device 210, the egressdevice 210 may process the traffic and transmit the traffic on a networklink, where the traffic exits virtual device 200.

An implementation, described herein, may automatically identify devicelinks, within a virtual device, that may be aggregated and aggregate thelinks so that the bandwidth of the links may be efficiently utilized.When a link changes state, the link may be easily added to or removedfrom a link aggregation and communication may continue withminimal-to-no loss of traffic. Also, shortest path calculations may beupdated to reflect the state change of the link so that traffic may beefficiently transmitted within the virtual device.

The foregoing description provides illustration and description, but isnot intended to be exhaustive or to limit the invention to the preciseform disclosed. Modifications and variations are possible in light ofthe above teachings or may be acquired from practice of the invention.

For example, while series of blocks have been described with regard toFIGS. 7-9, the order of the blocks may be modified in otherimplementations. Further, non-dependent blocks may be performed inparallel.

Also, certain portions of the implementations have been described as“logic” or a “component” that performs one or more functions. The terms“logic” or “component” may include hardware, such as a processor, anASIC, or a FPGA, or a combination of hardware and software (e.g.,software running on a processor).

Further, three separate tables have been described: a routing table, aforwarding table, and a connection table. In another implementation, twoor more of these tables may be combined into a single table. The term“table,” as used herein, may refer to any searchable form or arrangementof data within a memory device.

Also, reference has been made to aggregating links It is intended thatthe aggregation of links be synonymous to the aggregation of the portsto which these links are connected.

It will be apparent that aspects described herein may be implemented inmany different forms of software, firmware, and hardware in theimplementations illustrated in the figures. The actual software code orspecialized control hardware used to implement aspects does not limitthe embodiments. Thus, the operation and behavior of the aspects weredescribed without reference to the specific software code—it beingunderstood that software and control hardware can be designed toimplement the aspects based on the description herein.

Even though particular combinations of features are recited in theclaims and/or disclosed in the specification, these combinations are notintended to limit the disclosure of the invention. In fact, many ofthese features may be combined in ways not specifically recited in theclaims and/or disclosed in the specification. Although each dependentclaim listed below may directly depend on only one other claim, thedisclosure of the invention includes each dependent claim in combinationwith every other claim in the claim set.

No element, act, or instruction used in the present application shouldbe construed as critical or essential to the invention unless explicitlydescribed as such. Also, as used herein, the article “a” is intended toinclude one or more items. Where only one item is intended, the term“one” or similar language is used. Further, the phrase “based on” isintended to mean “based, at least in part, on” unless explicitly statedotherwise.

What is claimed:
 1. A virtual device, comprising: a plurality of devicesconnected to operate as a single device, where the plurality of devicesincludes a first device and a second device; and where the first deviceis to: transmit, via a plurality of ports, messages to discover one ormore of the plurality of devices, including the second device, identify,based on discovering the one or more of the plurality of devices, one ormore of the plurality of ports connected to each of the discoveredplurality of devices, determine, based on the identifying, that thefirst device connects to the second device via a plurality of links,where each of the plurality of links is associated with a different oneof the plurality of ports, automatically aggregate the plurality oflinks to form a link aggregation with the second device based ondetermining that the first device connects to the second device via theplurality of links, and transmit traffic to the second device via eachof the different ones of the plurality of ports.
 2. The virtual deviceof claim 1, where the first device is further to: create, in a table andbased on the identifying and the determining, an entry that storesinformation regarding the second device and information associated witheach of the plurality of links.
 3. The virtual device of claim 1, wherethe first device is further to: program one or more hardware components,of the first device, to distribute traffic on the plurality of links,via the different ones of the plurality of ports, using a load balancingtechnique.
 4. The virtual device of claim 1, where the first device isfurther to: monitor a state of each of the plurality of links,determine, based on the monitoring, that one of the plurality of linkschanged from a link up state to a link down state, remove the one of theplurality of links from the link aggregation to leave one or more of theplurality of links when the one of the plurality of links changed fromthe link up state to the link down state, and transmit traffic over theone or more of the plurality of links after removing the one of theplurality of links from the link aggregation.
 5. The virtual device ofclaim 1, where the first device is further to: receive informationregarding a topology of the virtual device, identify, based on thereceived information, an egress device, of the plurality of devices,where a received packet is transmitted to the egress device to betransmitted from the virtual device, and perform, based on receivedinformation, a shortest path calculation to to determine a path, forforwarding the received packet to the egress device, as a function of atotal bandwidth available on the link aggregation.
 6. The virtual deviceof claim 5, where, when transmitting the traffic to the second device,the first device is to: receive traffic on a network link, identify theegress device to receive the traffic, determine, based on the shortestpath calculation, that the traffic is to be sent to the second device,and transmit the traffic to the second device over one or more of theplurality of links of the link aggregation, via one or more of thedifferent ones of the plurality of ports.
 7. The virtual device of claim5, where the first device is further to: identify a new link connectedto the second device, where the new link is associated with another oneof the plurality of ports, automatically aggregate, based on identifyingthe new link, the new link with the link aggregation to form a new linkaggregation, and perform a new shortest path calculation to determine apath, for forwarding the received packet to the egress device, as afunction of a total bandwidth available on the new link aggregation. 8.The virtual device of claim 7, where, when transmitting the traffic tothe second device, the first device is to: receive traffic on a networklink, identify the egress device to receive the traffic, determine,based on the new shortest path calculation, that the traffic is to besent to the second device, and transmit, via at least one of theplurality of ports, the traffic to the second device over one or more ofthe plurality of links of the new link aggregation.
 9. The virtualdevice of claim 1, where the first device is further to: identify a newlink connected to the second device, where the new link is associatedwith another one of the plurality of ports, and automatically, based onidentifying the new link, aggregate the new link with the linkaggregation to form a new link aggregation.
 10. The virtual device ofclaim 1, where the plurality of devices include a plurality of networkdevices that are connected to operate as a single network device. 11.The virtual device of claim 1, where at least two of the plurality ofdevices are separated geographically by a distance of between 50kilometers and 100 kilometers.
 12. A virtual system, comprising: aplurality of devices, including a first device and a second device,connected to operate as a single device, and where the first devicecomprises one or more components to: discover, via one or more messagestransmitted via a plurality of ports of the first device, other ones ofthe plurality of devices, including the second device, identify, basedon discovering the other ones of the plurality of devices, one or moreof the plurality of ports connected to each of the other ones of theplurality of devices, determine, based on identifying the one or more ofthe plurality of ports, that the first device is connected to the seconddevice, identify, based on identifying the one or more of the pluralityof ports, a plurality of links and corresponding ones of the pluralityof ports that connect the first device to the second device,automatically aggregate, based on identifying the plurality of links andthe corresponding ones of the plurality of ports, the plurality of linksto form a link aggregation with the second device, and transmit, via oneor more of the corresponding ones of the plurality of ports, traffic tothe second device over one or more of the plurality of links, of thelink aggregation, using a load balancing technique.
 13. The virtualsystem of claim 12, where the one or more components are further to:monitor a state of each of the plurality of links, determine, based onthe monitoring, that one of the plurality of links changed to a linkdown state, remove the one of the plurality of links from the linkaggregation to leave a remaining one or more of the plurality of linkswhen the one of the plurality of links changed to the link down state,and transmit traffic over the remaining one or more of the plurality oflinks after removing the one of the plurality of links from the linkaggregation.
 14. The virtual system of claim 12, where the one or morecomponents are further to: receive information regarding a topology ofthe virtual system, determine, based on the received information, adevice, of the plurality of devices, for transmitting received packetsfrom the virtual system, and perform a shortest path calculation, forforwarding the received packets through the virtual system and to thedetermined device as a function of a total bandwidth available on thelink aggregation; and where, when transmitting the traffic to the seconddevice, the one or more components are to: receive traffic on a networklink, identify the determined device to receive the traffic, determine,based on the shortest path calculation, that the traffic is to be sentto the determined device via the second device, and transmit the trafficto the second device over the one or more of the plurality of links ofthe link aggregation.
 15. A method performed by a first device, of aplurality of devices connected to operate as a single device, the methodcomprising: transmitting, via one or more of a plurality of deviceports, messages to discover other ones of the plurality of devices;identifying, based on discovering the other ones of the plurality ofdevices, at least one of the plurality of device ports connected to eachof the other ones of the plurality of devices; determining, based onidentifying the at least one of the plurality of device ports, that thefirst device connects to a second device, of the plurality of devices,via a first link associated with a first device port of the plurality ofdevice ports, and a second link associated with a second device port ofthe plurality of device ports that is different from the first deviceport; automatically aggregating, based on determining that the firstdevice connects to the second device via the first device port and thesecond device port, the first link and the second link to form a linkaggregation with the second device, and transmitting, via the firstdevice port and the second device port, a plurality of packets to thesecond device via the first link and the second link of the linkaggregation, based on aggregating the first link and the second link,where one or more of the plurality of packets are transmitted via thefirst link and another one or more of the plurality of packets aretransmitted via the second link.
 16. The method of claim 15, furthercomprising: storing information that associates the second device withthe link aggregation; and using the stored information to program one ormore components of the first device to distribute the plurality ofpackets across the first link and the second link.
 17. The method ofclaim 15, further comprising: monitoring a state of the first link andthe second link; determining, based on the monitoring, that a particularlink, of the first link and the second link, changed to a link downstate; removing the particular link from the link aggregation to leave aremaining link, of the first link and the second link, in response todetermining that the particular link changed to the link down state; andtransmitting a packet on the remaining link after removing theparticular link from the link aggregation.
 18. The method of claim 15,further comprising: receiving, via the plurality of device ports,information regarding a topology associated with the plurality ofdevices; and performing a shortest path calculation to one of theplurality of devices as a function of a total bandwidth available on thelink aggregation.
 19. The method of claim 18, where transmitting theplurality of packets to the second device includes: receiving, via anetwork port of the first device, a packet on a network link,identifying the one of the plurality of devices to receive the packet,determining, based on the shortest path calculation, that the packet isto be sent to the second device, selecting the first link or the secondlink on which to transmit the packet to the second device, andtransmitting the packet on the selected first link or the selectedsecond link.
 20. The method of claim 18, further comprising: identifyinga third link connected to the second device, where the third link isassociated with a third device port, of the plurality of device ports,that is different from the first device port and the second device port;automatically aggregating, based on identifying the third link, thethird link with the link aggregation to form a new link aggregation; andperforming a new shortest path calculation to the one of the pluralityof devices as a function of a total bandwidth available on the new linkaggregation.
 21. The method of claim 20, where transmitting theplurality of packets to the second device includes: receiving, via anetwork port of the first device, a packet on a network link,identifying the one of the plurality of devices to receive the packet,determining, based on the new shortest path calculation, that the packetis to be sent to the second device, selecting the first link, the secondlink, or the third link for transmitting the packet to the seconddevice, and transmitting, via the first device port, the second deviceport, or the third device port, the packet on the first link, the secondlink, or the third link based on the selecting.
 22. The method of claim15, further comprising: identifying a third link connected to the seconddevice via a third device port of the plurality of device ports; andautomatically aggregating the third link with the link aggregation toform a new link aggregation based on identifying the third link.